1 8 Memoirs of the Indian Museum. [Voiv. I, 



Indian Museum shows that externally the black form is identical with the old Black 

 Rat of England.^ The belly is a very dark grey or greyish-black ; the feet are covered 

 with short black or brown hair and are atreous throughout, including the soles. A few 

 grey hairs may be found mixed with the black on the sides. Except that none of the 

 8 specimens exceed 16-5 cm. in length, there is nothing in either the body or the cranial 

 measurements to distinguish them from normally coloured rats, for the fact that the 

 tail is a little below the average is probably accidental and of no importance. The 

 underfur instead of being grey may be nearly black. In the belly it may have a few 

 orange ochraceous tips, giving rise to a greenish tint in combination with the dark blue- 

 grey of the underfur, just as is sometimes seen in the back of the rat of ordinary colour, 

 particularly when wet. I am at present trying to breed from a female, which is interest- 

 ing as being intermediate between the extreme melanotic type and what is much more 

 common, the rat that is simply slightly darker than usual and more pigmented all over. 

 Though at a first glance this rat seemed black all over, a closer inspection showed that 

 the sides were brown owing to an admixture of the black with yellow and ochraceous 

 rufous tips. The belly and throat were very dark-grey and the feet were atreous. 

 The most notable thing in the colouring was a jet black patch under the throat, stretch- 

 ing from ramus to ramus. 



Unpigmented Forms. — Just the converse of the melanotic forms are the sports 

 which are occasionally come across showing lack of pigment all through the skin as 

 well as the hair. The most extreme case has been admirably figured and needs no 

 detailed description. It is a very good specimen of partial albinism, where pigment 

 has been retained in the eye and in the dorsal stripe, but elsewhere is lost. One other 

 instance has been met with in which there were only sufficient white hairs to give 

 the rat a light greyish tint. A more interesting form was one in which it was less a 

 case of pigment being wanting than of its being very faint. The skin it is true was 

 unpigmented upon the dorsal as well as the ventral aspect, but the fine fur of the back 

 was brown, so light in colour as to be almost yellow, i.e., a pale cinnamon colour. 

 Unfortunately the skull of this specimen was lost before being examined ; the general 

 dimensions and appearance of the specimen agreed closely with the description of 

 Mus fulvescens ^ or cinnamoneus, a rat about the specific identity of which I am rather 

 doubtful. 



Fur. — From the preceding section it will be evident that to attempt to express 

 in terms of fur the extreme variations of colour found, would be impossible. The 

 fur varies greatly in consistency, being sometimes comparatively soft and fine and quite 

 free from spines, while in others a good many spines will be found taking the place of 

 the intermediate elements. In none of the skins do spines form the predominant 

 element of the covering ; as a rule they are rather few and scattered. The usual 

 three elements are found — 



I. Dark-grey fine underfur about 75 cm. long. — In the white-bellied forms 



^ See, however, note at end of paper. 



^ Some of the Indian Museum specimens of M. fulvescens have the zygomatic plate sloped forward 

 but others have it perpendicular. 



